1. Field of the Invention
The present invention relates to a battery load power detecting system for detecting a load power of a battery connected to a load group including a steering device for providing a steering torque by a motor and to a generator driven by an engine.
2. Description of the Related Art
In a steering-by-wire type steering device in which there is no mechanical connection between a steering wheel and a steering gear box, and a control means controls the driving of a motor mounted in the steering gear box based on an electric signal generated by the operation of the steering wheel thereby steering left and right wheels, if the state of a battery as a power source is deteriorated, there is a possibility that the steering of the wheels cannot be reliably carried out. Therefore, it is necessary to conduct the maintenance or replacement of the battery while accurately monitoring the load state of the battery.
A conventional power supply system for such a steering-by-wire type steering device has a single current sensor which is mounted on a line extending from the battery and a generator to a load group including the steering-by-wire type steering device, and the current sensor detects a load current supplied from the battery and/or the generator to the load group, thereby determining the load state of the battery.
The determination of the deteriorated state of a regular lead battery to be mounted on a vehicle is carried out based on an internal impedance, a specific gravity and temperature of a liquid electrolyte and the like, but such determination is troublesome, and determination accuracy is not satisfactory.
Published Japanese Translation No. 2002-542576 of PCT/US00/09705 and Japanese Patent Application Laid-open No. 2002-190329 disclose a system which performs life lengthening and determination of the deterioration of a battery, and Japanese Patent Application Laid-open No. 6-54402 discloses a system which measures remaining capacity of a battery for an electric vehicle.
In a system in which a current supplied to a load group is detected by a single current sensor, as in the power supply system for the conventional steering-by-wire type steering device, it is impossible to determine whether the current is supplied from a battery or a generator, so that it is impossible to properly determine the load state of the battery by detecting a current flowing directly into and out of the battery.